The second photo in this thread might be useful.
http://www.pprune.org/rotorheads/509...ous-500-a.html
This is one of the few photos of the YOH-6A with the rear tank visible. The FAI website had few more photos of this helicopter but I can't find them at the moment.
If you want to read more about the series of record setting flights from 1966, you could do worse than have a look at this book.
Howard?s Whirlybirds<BR>Howard Hughes? Amazing Pioneering Helicopter Exploits<BR><I>Donald J. Porter</I> - Detailed item view - Fonthill Media
It has an entire chapter dedicated to the record flights.
500 Fan.